The Enneagram is a nine-sided geometrical figure associated with George Gurdjieff. Attempts have been made to trace it back to the Sufis, but this has been disputed. More recently than Gurdjieff, scholars such as Claudio Naranjo and Oscar Ichazo have developed a personality typology based on the Enneagram. That says there are nine personality types, each known by a number from One to Nine. 
- Nogosek and O'Leary's (1984) book "The Enneagram: A Journey of Self-Discovery"